NMDA Receptor Blockade and Spinal Cord Ischemia Due to Aortic
Crossclamping in the Rat Model
F Follis, K Miller, OU Scremin, S Pett, R Kessler and J Wernly
Abstract:
Recent brain research proposes that, during ischemia,
synaptically released excitatory amino acid neurotransmitters
accumulate at toxic concentrations with ensuing neuronal death.
Their action is mediated by the receptor subtype N-methyl-D-aspartate
(NMDA). The protective effect of NMDA receptor blockade with
intrathecal MgSO4 and MK-801 was investigated during
spinal cord ischemia induced by aortic occlusion of 12 minutes.
Male Sprague-Dawley rats, 250-300g, underwent intrathecal administration
of 20 µL of normal saline (SA n = 16), MgSO4
1M (MG n = 16), or MK-801, 25 mM solutions (MK n = 16) in a
randomized order. After 2 hours, the animals underwent occlusion
of the thoracic aorta and subclavian arteries for 12 min. An
additional control group (CO n = 16) underwent occlusion for
12 minutes, without intrathecal injection. The animals were
scored according to their functional performance (LS = lesion
score) each day for four days by a blinded observer. Mean LS
were calculated for each group at a given day. Treatment and
control groups were not different at day 1 (P = 0.302). Group
MG was improved from groups SA (P = < 0.0039) and CO (P =
< 0.0048) at day 4. This study demonstrates that although
intrathecal NMDA receptor blockade with MgSO4 or
MK-801 does not prevent paraplegia due to spinal cord ischemia
in the rat, it could however influence the rate of recovery
after ischemic injury.
|
Can.
J. Neurol. Sci. 1994; 21: 227-232
|
|
